Hi all,

1- The issue at hand.
- Our BMW X5 2021 purchased in U.A.E, for some odd reasons, has no panic button on its FOB. As such it is a pain to find the car in congested parking lots when we forget where we parked the damn thing.
I have discussed it with the dealer, but contrary to their initial claims, they could not figure that out either. The button on the FOB which is supposed to be designated to panic functionality, can be programmed to open up the trunk door, turn on lights around the car etc., but will not activate horn. I suppose it has some thing to do with the law in here, yet our Mercedes Bens E300-2016 which was purchased here too, does have panic button which we find extremely useful. We want a panic button, plain and simple.

2- Objective.
- To find out the best and easiest way to use existing FOB, or my mobile phone to activate car's existing horn, or an added buzzer for panic/find functionality. I do not wish to purchase aftermarket Tranmitter/Receivers which would do the task, because that would necessitate another FOB that we abhor to carry with us.

3- What I have done so far and what I am thinking about.
A- I thought since the FOB can be used to open up the trunk of the car remotely, I can take 12V from the trunk's door switch (when it is opened remotely) to activate a circuit. The first circuit that I came up with is the following (didn't want to use Arduino yet, just good old electronics ).

B- The little circuit utilizses NE555 timers so that when it is powered up with 12V (trunk door gets open), it will wait 15 sec, then activates/de-activate a buzzer in 25 seconds intervals for ever (or until you close the trunk door). The buzzer will beep every second within activation periods.

C- Note: The initial 15 sec delay is when you are near the ar and normally open up the trunk and do not wish to hear the buzzer. In such cases we know we have 15 sec to turn off a switch on the circuit box installed on the wall of the trunk. I know, this solution is not that elegant, my wife in particular woldn't like it.

D- I have looked at Blynk.cc technology to use their app on my mobile phone to activate a pin on Arduino Nano remotely (WiFi), yet as I understand, the Nano installed inside the car has to have internet connection as well. To the best of my knowledge, we don't' have internet service for cars in here. So, this seems to be out of the question. It seems that Blynk has developed a Blue Tooth system that will allow the a mobile phone to connect directly to Nano, but of course Blue Tooth's limited range would not do the trick in this application.

So, what do you think? Shall I stick to my first approach (item A-B-C) or you can think of a better solution. My preferred method is to use Mobile Phone, but as said in item D, it seems that I need internet connection inside the car.

Cheers all,

Mohammad

 

If the signal to the boot opener is still produced when the open boot button is pressed and the boot is already open then you could have a circuit which detects two boot open button presses to activate the noise. Then a single press will only open the boot.

 

Hello. Does your X5 have an alarm system? I find the panic button really obnoxious so on mine I unlock and lock the car to hear the "armed" confirmation beep instead. It works pretty well.

 

If the signal to the boot opener is still produced when the open boot button is pressed and the boot is already open then you could have a circuit which detects two boot open button presses to activate the noise. Then a single press will only open the boot.

Hi, if boot/trunk is already opened, pressing the trunk button on the FOB will close the trunk. I have not examined the trunk switch yet. My first assumption is that when the trunk is closed (resting), the trunk door switch must be in open status, otherwise battery would go flat over time. My second assumption is that when trunk is opened, the switch get 12V to be sent to the car computer so that the computer knows trunk is opened. This is the signal I think I can also use to activate my circuit. When the trunk is closed, this switch loses power again which in turn renders my circuit inactive.

If the signal to the boot opener is still produced when the open boot button is pressed and the boot is already open then you could have a circuit which detects two boot open button presses to activate the noise. Then a single press will only open the boot.

Hi, if boot/trunk is already opened, pressing the trunk button on the FOB will close the trunk. I have not examined the trunk switch yet. My first assumption is that when the trunk is closed (resting), the trunk door switch must be in open status, otherwise battery would go flat over time. My second assumption is that when trunk is opened, the switch gets 12V to be sent to the car computer so that the computer would know trunk is opened. This is the signal I think I can use to activate my circuit. When the trunk is closed, this switch loses power again which in turn renders my circuit inactive.

 

Some things in cars are activated by grounding a terminal, rather than applying 12V. Also, the car's computers may be expecting +5V signals, not +12V. Are you sure which way your car is wired?

 

Hello. Does your X5 have an alarm system? I find the panic button really obnoxious so on mine I unlock and lock the car to hear the "armed" confirmation beep instead. It works pretty well.

Hello back, well this car came with all the options we could get, yet does not chirp then you lock it, I wish it did. With the Benz, the actual horn is activated when panic button is pressed; I know it is loud but that kind of serves the purpose of finding it, considering the annoying experience of not finding your car in Summer heat of Dubai with car fumes in underground parkings of shopping malls, it seems a small price to pay.

 

A lot of things in cars are activated by grounding a terminal, rather than applying 12V. Are you sure which way yours is wired?

No I am not sure, but I am not at that stage either. I guess I can use relays or alike to flip a signal either way, as long as I have a filliping signal to work with. At this stage I do not consider it a showstopper. Cheers

 

I believe that can be coded. Perhaps you should enquire at the dealer.

 

I believe that can be coded. Perhaps you should enquire at the dealer.

Do you mean chirping? I searched the eintire user manual, the word"chirp" is nowhere to be found. As said before, the dealer staff, with differenct level of experties, told me they could do it, but could not. Also, on another subject, we cannot enter GPS coordinates directly into Navigation system (while our 6 year old Mercedes allows it), and delar said it is possible, but could not find any option to do it either. It is odd indeed.

 

Do you mean chirping? I searched the eintire user manual, the word"chirp" is nowhere to be found. As said before, the dealer staff, with differenct level of experties, told me they could do it, but could not. Also, on another subject, we cannot enter GPS coordinates directly into Navigation system (while our 6 year old Mercedes allows it), and delar said it is possible, but could not find any option to do it either. It is odd indeed.

Well, the coding options won't appear in the manual, they are part of the long list of optional behaviors (like folding the mirrors when turning off the car, or not). Have you tried the BMW-specific forums to see if anyone has a clue? BMW key fobs have "hidden" functions which vary by model. Usually these can be turned in the iDrive settings but they can be obscure. For example some cars provide a remote start if you press the lock button twice, then hold.

I wonder if there is a way to make your panic work by using a non-obvious key press?

 

Well, the coding options won't appear in the manual, they are part of the long list of optional behaviors (like folding the mirrors when turning off the car, or not). Have you tried the BMW-specific forums to see if anyone has a clue? BMW key fobs have "hidden" functions which vary by model. Usually these can be turned in the iDrive settings but they can be obscure. For example some cars provide a remote start if you press the lock button twice, then hold.

I wonder if there is a way to make your panic work by using a non-obvious key press?

That is a good idea, BMW forums that is. Thanks for the input Yaakov

 

A fairy simple option is to require two actions to sound the horn. First, the remote switching on of the lights could also operate a relay to route the trunk unlock signal to instead sound the horn. No software, no complex logic scheme, and no timer. Just a single relay.. In addition, having the lights on will help locate the car.

 

A fairy simple option is to require two actions to sound the horn. First, the remote switching on of the lights could also operate a relay to route the trunk unlock signal to instead sound the horn. No software, no complex logic scheme, and no timer. Just a single relay.. In addition, having the lights on will help locate the car.

Thanks, it is indeed is a viable solution. In fact could be a bit simpler. This car allows me to program one the keys on the FOB to a number of actions: open the trunk, turn on rear lights and side lights at the same time, light up from lights (low beam), so if I program it to turn on lights only ( leaving trunk door alone), I don't need to play with the trunk swish. The only issue is that when the lights comes on after the button on FOB is pressed, lights stay on for a good 15~20 second before they go off. This is a long and annoying time to have a powerful horn on. It is preferable if the horn beeps (with the original frequency). This then necessitates the NE555 timer circuit that I have already put together, agreed?

 

Thanks, it is indeed is a viable solution. In fact could be a bit simpler. This car allows me to program one the keys on the FOB to a number of actions: open the trunk, turn on rear lights and side lights at the same time, light up from lights (low beam), so if I program it to turn on lights only ( leaving trunk door alone), I don't need to play with the trunk swish. The only issue is that when the lights comes on after the button on FOB is pressed, lights stay on for a good 15~20 second before they go off. This is a long and annoying time to have a powerful horn on. It is preferable if the horn beeps (with the original frequency). This then necessitates the NE555 timer circuit that I have already put together, agreed?

I would think installing an independent annunciator of some kind would be better than the horn in order to interfere as little as possible with the car’s systems. BMWs have a lot of computerization and while it might not be a problem to try to operate the horn independently of the car’s own system it could be. Making a high impedance connection to the light circuit seems far less fraught.

Just me being very cautious as I would be if I was trying this for myself.

I think I just might consider using an additional, third party fob to run a completely independent system… or make it a point to use my phone to take photo of where I park.

 

I think I'd just use a suction cup to mount a tiny flag on the car roof. Or does everyone in Dubai go around with flags on their cars?

 

Thanks, it is indeed is a viable solution. In fact could be a bit simpler. This car allows me to program one the keys on the FOB to a number of actions: open the trunk, turn on rear lights and side lights at the same time, light up from lights (low beam), so if I program it to turn on lights only ( leaving trunk door alone), I don't need to play with the trunk swish. The only issue is that when the lights comes on after the button on FOB is pressed, lights stay on for a good 15~20 second before they go off. This is a long and annoying time to have a powerful horn on. It is preferable if the horn beeps (with the original frequency). This then necessitates the NE555 timer circuit that I have already put together, agreed?

YES, and it may be that simply adding that timer connection will cause a string of beeps, that are more acceptable.

 

I think I'd just use a suction cup to mount a tiny flag on the car roof. Or does everyone in Dubai go around with flags on their cars?

Well, BMW should condider this; a retracting sort of a flag.

 

Well, BMW should condider this; a retracting sort of a flag.

A retracting flag would soon be popular and thus no longer unique. That would reduce the benefit.
If everybody does it, it does not stand out.